Electronic printing device

ABSTRACT

An electronic printing device having an electrostatic printing tube or film penetration tube and a finely meshed screen of dielectric material. In the device, a positive charge is supplied to printing ink retained within the meshes of the screen or to a recording medium of conventional paper material, while a negative charge is supplied to the recording medium or to the printing ink according to a pattern determined by a signal so as to utilize the electrostatic force of attraction between the positive and negative charges for producing a print.

United States Patent 1191 Maeda et a1.

ELECTRONIC PRINTING DEVICE Inventors: Haruo Maeda, Tokyo; Eiichi Miyazaki, lrumacho, Chofu-shi, both of Japan Assignee: Matsushita Electric Industrial Co.,

Ltd., Osaka, Japan Filed: July 12, 1968 Appl. No.: 744,552

Foreign Application Priority Data July 25, 1967 Japan 42/48285 July 26, 1967 Japan ..42/48544 US. Cl. 101/153, l01/DIG. 13, 101/150,

346/74 CR, 346/74 ES Int. Cl B4" 9/00 Field of Search 101/150, 170, DIG. 13,

References Cited UNITED STATES PATENTS 9/1961 Walkup l01/DIG. 13 9/1962 Schaffert 101/DIG. 13 7/1963 Schaffert l0l/DIG. 13

[4 June 12, 1973 3,188,649 6/1965 Preisingeretal. 101/1910. 13 3,220,833 11/1965 McFarlane l0l/D1G. 13 3,257,222 6/1966 Carlson 101/1310. 13 3,279,367 10/1966 Brown 101/010. 13 3,340,803 9/1967 Childress et a1. ..101/p10.13 3,355,743 11/1967 .Capps ..101/1)10.13 3,377,598 4/1968 Borman 101/010. 13

Primary Examiner-Edgar S. Burr Attorney-Stevens, Davis, Miller & Moshe r [57] ABSTRACT An electronic printing device having an electrostatic printing tube or film penetration tube and a finely meshed screen of dielectric material. In the device, a positive charge is supplied to printing ink retained within the meshes of the screen or to a recording me dium of conventional paper material, while a negative charge is supplied to the recording medium or to the printing ink according to a pattern determined by a signal so as to utilize the electrostatic force of attraction between the positive and negative charges for producing a print.

7 Claims, 6 Drawing Figures ELECTRONIC PRINTING DEVICE This invention relates to an electronic printing device of the type in which a print can be obtained by depositing printing ink on a recording sheet depending on the amount of electrical charges distributed in a pattern representing a signal derived from means such as an electrostatic printing tube or film penetration tube.

Conventional electronic printing devices which have been put into practical use or are still in an experimental stage include the combination of a fiber optics tube FOT and an electrophotographic recording sheet, and the combination of an electrostatic printing tube EPT or a film penetration tube FPT and an electrostatic recording sheet. The former type of electronic printing devices employs an electrophotographic sensitive sheet or photographic sensitive sheet and utilizes the photoelectric effect or conventional sensitization to obtain a print, while the latter type of electronic printing devices both employ an electrostatic recording sheet and resort to the dry or wet development by a toner phenomenon to obtain a print. While both these two types of electronic printing devices have their merits and demerits, it is an undeniable fact that they require a special electrophotographic recording sheet, photographic sensitive sheet and electrostatic recording sheet as a recording medium.

It is therefore a primary object of the present invention to provide a novel and useful electronic printing device which does not require those special recording sheets and can mechanically and electronically transfer a printing ink onto a sheet of conventional paper material thereby simply obtaining a print.

The electronic printing device according to the present invention employs an electrostatic printing tube EPT having a recording head of such a structure that a multiplicity of fine pins arranged in a single row or a plurality of rows are embedded at their root in the surface of the face plate of the tube, or a film penetration tube FPT having a recording head of such a structure that a thin film of metal or nonmetal covers the surface of the face plate of the tube so that a recording electron beam emanating in a vacuum region within the tube is passed through the thin film to the atmosphere. The electronic printing device utilizes the charge of electrons thus led outwardly from the tube so that printing ink of an electrically insulating nature preliminarily retained within the meshes of a recording screen is transferred to the surface of a sheet of conventional paper material in the air by the electrostatic force of attraction between electrical charges of opposite polarity thereby effecting the desired electronic printing.

The above and other objects, features and advantages of the present invention will be apparent from the following description when taken in conjunction with the accompanying drawings, in which:

FIGS. 1 and 2 are schematic views illustrating two typical methods of electrostatic printing according to the present invention;

FIGS. 3a and 3b are a schematic side elevation and a plan view, respectively, of the electronic printing device preferably used for the practice of the method shown in FIG. 1; and

FIGS. 4a and 4b are schematic side elevation and a plan view, respectively, of the electronic printing device preferably used for the practice of the method shown in FIG. 2.

Referring to FIG. 1 showing one basic form of the electrostatic printing mechanism according to the invention, any excess of printing ink particles 51 filling the meshes 54 of a cylindrical ink screen 5 is sufficiently removed to such an extent that the ink particles 51 define a concave surface relative to the surface of the screen 5 due to the surface tension and are held within the meshes 54 of the screen 5 in a state as shown. The ink screen 5 thus impregnated with the printing ink is rotated in the direction of the arrow as a drum 55 carrying the ink screen 5 is rotated, and the ink particles 51 within the meshes are negatively charged with electrons conducted through a recording head (not shown) in an amount corresponding to the degree of modulation of the electron beam by a signal. A sheet of paper 11 is arranged to pass between the ink screen 5 having within its meshes the printing ink particles 51, which are negatively charged depending on the signal, and a paper feed roll 13 which is kept at a high positive potential. Because of the fact that the paper 1 1 is continuously fed between the rotating ink screen 5 and the feed roll 13, the negatively charged ink particles 51 retained within the meshes of the ink screen 5 are successively attracted toward the positive charge on the roll 13 and are thereby deposited on the paper 11. The ink particles are transferred onto the paper 11 as at 53 and thus the pattern representing the applied signal can be printed on the paper 11.

Referring to FIG. 2 showing the other basic form of the electrostatic printing mechanism, there is illustrated the step in which printing ink is being transferred to a sheet of paper or film 11 by the electrostatic force of attraction. An electron beam 4 is produced in an electrostatic printing tube or film penetration tube 1 for scanning across a recording head 2 and is passed through the recording head 2 comprising a multiplicity of electron-transmitting recording pins or a thin electron-previous film to supply the negative charge to that surface of the paper or film 11 which is opposite to the recording'head 2. On the other hand, ink particles 51 filling the meshes S4 of a cylindrical ink screen 5 have already been positively charged as at 52 by a positive charge supplier (not shown). Therefore, the negative charge supplied to the reflecting surface of the paper or film 11 by the electron beam 4 in response to scanning by the electron beam 4 across the recording head 2 attracts the positively charged ink particles 52 toward it, with the result that the ink particles 52 are transferred onto the other surface of the paper or film 11 as at 53. The cylindrical ink screen 5 and the paper or film l l are gradually separated away from each other as the paper or film 11 moves downwardly in the figure in the direction of the arrow. A print is thereby produced in which those positively charged ink particles 53 which are attracted by the negative charge supplied by the electron beam 4 are deposited on the paper or film 11 in accordance with the pattern given by the signal.

In this case, it will be seen that any excess of the ink particles 51 filling the meshes 54 of the cylindrical ink screen 5 in the upper part of FIG. 2 is sufficiently removed so that the ink particles 51 have a concave surface relative to the surface of the cylindrical screen 5 due to the surface tension and are held within the meshes 54 in a state as shown. Therefore, when the electron beam 4 is not scanning across the recording head 2, no negative charge appears on the opposite side of the paper or film l1 and the positively charged ink particles 52 within the meshes 54 are not attracted toward the paper or film 11. Since, in such a case, the ink particles 52 do not contact the paper or film 11, the paper or film 11 moves away from the cylindrical ink screen without the ink being transferred onto the paper or film 11 as the latter travels downwardly.

Referring to FIGS. 3a and 3b showing in elevation and plan an embodiment of the invention for the practice of the method of electrostatic printing schematically illustrated in FIG. 1, an electrostatic printing tube or film penetration tube I is provided with a recording head 2 and an electron gun 3 for emitting an electron beam 4. The recording head 2 in the former tube is in the form of a pin head which has such a structure that a multiplicity of fine conductor pins arranged in a single row or a plurality of rows are embedded at their root in the surface of the face plate at a rate of a few to ten pieces per square millimeter of the area of the face plate, while in the latter tube, the recording head 2 has an electron-pervious thin film of metallic or nonmetallic material so as to forwardly transmit the charge of the electron beam 4 modulated depending on a signal. A cylindrical ink screen 5 of more than severalhundred meshes made from a dielectric material such as plastics is mounted on a grounded metal drum 55 for rotation with the latter and is in rotary contact with the recording head 2. An applicator roll 6 is provided to apply printing ink 8 contained in an ink reservoir 7 to the screen 5. Any excess of the printing ink 8 filling the meshes of the screen 5 is removed by a doctor blade 10. A web of recording sheet 11 is wound around a supply roll 12 and is fed by a feed roll 13 of metal in the direction of the arrow while contacting the screen 5 during its traveling movement. A positive charge supplier 14 supplies positive charges to the feed roll 13.

In the printing operation, the printing ink 8 contained in the ink reservoir 7 attaches to the surface of the applicator roll 6 as an ink layer 9 by its own viscosity and the ink layer 9 attaching to the surface of the applicator roll 6 is then applied to fill the meshes of the screen 5. Any excess of the ink attaching to the surface of the screen 5 is removed by the doctor blade so that the ink particles exist solely within the meshes of the screen 5 and do not entirely remain on the surface of the screen 5. Thus, no ink transfer results by mere contact of the recording sheet 11 with the surface of the screen 5.

By virtue of such an arrangement, the ink particles within the meshes of the screen 5 to which the negative charge is supplied from the recording head 2 of the electrostatic printing tube or film penetration tube 1 are transferred from within the meshes onto the recording sheet 11 in accordance with the printing mechanism described with reference to FIG. 1 and thus electrostatic printing can be effected on the recording sheet 11 to produce a print 15.

It will be understood from the above description that the present invention eliminates theneed for employment of a conductive coloring agent such as carbon and can deposit conventional printing ink on a recording medium of conventional sheet material depending on the amount of a signal-modulated electric charge delivered from an electrostatic printing tube or film penetration tube. Thus, the electronic printing device of small size according to the present invention can effect highspeed printing with conventional printing ink.

Referring to FIGS. 4a and 4b showing in elevation and plan another embodiment of the invention for the practice of the method of electrostatic printing schematically illustrated in FIG. 2, an electrostatic printing tube or film penetration tube 1 is provided with an electron gun 3 for emitting an electron beam 4. As in the preceding embodiment, the electrostatic printing tube or film penetration tube 1 is provided with a recording head 2 for similarly leading the electrical charge outwardly from the tube. A cylindrical ink screen 5 of more than several-hundred meshes made from a dielectric material such as plastics is mounted on a drum of electrically insulating material for rotation with the latter and is in rotary contact with the recording head 2. An applicator roll 6 is provided to apply printing ink 8 contained in an ink reservoir 7 to the screen 5. Any excess of the printing ink 3 filling the meshes of the screen 5 is removed by a doctor'blade 10. A web of recording sheet 11 of electrically insulating paper or plastic material is wound around a supply roll 12 and fed between the recording head 2 and the rotating screen 5 in the direction of the arrow. A positive charge supplier 14 supplies positive electrostatic charges to the cylindrical ink screen 5.

In the printing operation, the applicator roll 6 draws up the printing ink 8 from the ink reservoir 7 so that the ink 8 attaches to the application roll 6 as an ink layer 9. The ink layer 9 attaching to the surface of the applicator roll 6 is then applied to fill the meshes of the screen 5. Any excess of the ink attaching to the surface of the screen 5 is wiped away by the doctor blade 10 so that the excess of the ink may not foul the recording sheet 11. In FIG. 4a, the cylindrical ink screen 5 is rotated in the direction of the arrow so that the recording sheet 11 of electrically insulating paper or plastics is fed between the recording head 2 of the electrostatic printing tube or film penetration tube 1 and the rotating screen 5 is moved downwardly at a constant speed. The supplier 14 of a high-potential positive charge is operative to positively charge the cylindrical ink screen 5 whose meshes are filled with the ink particles drawn up from the ink reservoir 7. As a result, the ink particles filling the meshes of the screen 5 are also charged with the high-potential positive charge. The amount of electrical charge supplied to the ink is dependent upon the voltage of the charge supplier 14 and the electrostatic capacity of the ink with respect to the ground.

The printing mechanism in the present embodiment will now be described. When the electron beam 4 sub ject to modulation depending on the amount of a signal applied thereto scans across the recording head 2 of the electrostatic printing tube or film penetration tube It, the electrical charge of the electron beam 4 is led outwardly through the charge-transmitting recording pins of the electrostatic printing tube or through the electron-pervious thin film of the film penetration tube 1 to be transferred onto the recording sheet 11 of electrically insulating material at the surface closer to the recording head 2, thereby forming on that surface a pattern of the negative charge supplied by the electron beam 4. Thus, the ink particles having already been positively charged and filling the meshes of the cylindrical ink screen 5 are attracted toward the recording sheet 11 depending on the negative charge existing thereon and attach to the surface of the recording sheet 11. In FIG. 4a, the cylindrical screen 5 and the recording sheet 11 are separated from each other as the recording sheet 1 1 moves downwardly, and a print is produced on the sheet I 1 in which the ink particles bearing the positive charge are transferred onto the sheet 11 by being attracted by the negative charge supplied by the electron beam 4.

In connection with the above printing process, it will be seen that any excess of ink particles filling the meshes of the cylindrical screen 5 in the upper part of FIG. 4a is sufficiently wiped away so that the ink particles have a concave surface relative to the surface of the cylindrical screen 5 due to the surface tension and are held within the meshes as shown in FIG. 2. Therefore, when the electron beam 4 is not scanning across the recording head 2, no negative charge appears on the opposite side of the recording sheet 11 and the positively charged ink particles within the meshes are not attracted toward the recording sheet 11. Since, in such a case, the ink particles do not contact the recording sheet 11, the recording sheet 11 moves away from the cylindrical screen 5 without the ink being transferred onto the recording sheet 11 as the latter travels downwardly.

In the embodiment shown in FIGS. 4a and 4b, the cylindrical screen 5 may have any suitable shape including a meshed cylindrical roll or meshed endless belt insofar as it is made from a dielectric material and is mounted for rotation with a drum of electrically insulating material. In whatever system that may be employed, it is essential, after filling the ink within the meshes of the screen 5, to apply a sufficient squeezing pressure to the screen 5 to remove any excess of the ink from the meshes so that the ink particles can be retained within the meshes while having a concave con tour and to sufficiently wipe away the ink from the surface of the screen 5. Furthermore, the charging of the ink with the positive charge by the positive charge supplier 14 in the latter embodiment must suitably be regulated taking into consideration the transferability of the ink to the recording sheet.

It will be appreciated fromthe foregoing description that the present invention utilizes the electrostatic force of attraction between positive and negative charges for the electrostatic printing with printing ink. According to the present invention, any conventional printing ink can directly be deposited on a recording medium of conventional sheet material using an electrical charge of a signaLmodulated electron beam derived from an electrostatic printing tube or film penetration tube, and any special recording medium such as a special recording sheet or sensitive sheet and developing and other treatment required in electrophotography are utterly unnecessary. Furthermore, the electronic printing device according to the invention has a simple structure, can provide a picture of good quality and is capable of printing the picture on a sheet of conventional paper material with conventional printing ink at a high speed since the ink retained within the meshes of the screen is merely attracted to deposit on the recording sheet in a pattern corresponding to a static electrical charge image formed thereon.

What is claimed is:

1. An electronic printing device comprising a screen of dielectric material impregnated with printing ink; means generating a modulated electron beam signal; means depositing said ink on a recording medium in a pattern representing the strength of said signal by the electrostatic force of attraction between charges'of opposite polarity, said depositing means including means supplying a charge of first polarity to said ink in an amount dependent upon the strength of said signal, and

. means supplying a uniform charge of polarity opposite to that of said first polarity to said recording medium; and means bringing said recording medium and said screen into operative engagement with each other.

2. An electronic printing device comprising a screen of dielectric material impregnated with printing ink, means for supplying a negative charge of electrons to the ink particles retained within the meshes of said screen in a pattern depending on a signal derived from electron beam generating means thereby negatively charging said ink particles, and transfer printing means bearing a positive charge and operative to cause deposition of said negatively charged ink particles on a recording medium with its positive charge as said recording medium is passed between it and said screen.

3. An electronic printing device according to claim 2, in which a cathode-ray tube is provided so that the electrical charge in an amount determined by said signal can be transmitted outwardly from said tube through the face plate thereof thereby supplying to said ink particles the negative charge in a pattern which is dependent on the signal.

4. An electronic printing device comprising a screen of dielectric material impregnated with printing ink; means generating a modulated electron beam signal; means depositing said ink on a recording medium in a pattern representing the strength of said signal by the electrostatic force of attraction between charges of opposite polarity, said depositing means including means supplying a charge of first polarity to said recording medium in an amount dependent upon the strength of said signal and means supplying a uniform charge of a polarity opposite to that of said first polarity to said printing ink; and means bringing said recording medium and said screen into operative engagement with each other.

5. An electronic printing device according to claim 4, in which a cathode-ray tube is provided so that the electrical charge in an amount determined by said signal can be transmitted outwardly from said tube through the face plate thereof thereby supplying to said recording medium a negative charge in a pattern which is dependent on the signal.

6. An electronic printing device comprising a screen of dielectric material wound around a drum and impregnated with printing ink, means for supplying a negative charge of electrons to the ink particles retained within the meshes of said screen in a pattern depending on a signal thereby negatively charging said ink particles, and a feed roll bearing a positive charge and operative to 'feed a recording sheet so that said recording sheet is fed between said roll and said screen.

7. An electronic printing device comprising a screen of dielectric material wound around a drum and impregnated with printing ink, means for uniformly supplying a positive charge to the ink particles retained within the meshes of said screen, and means disposed opposite to said screen with a recording sheet interposed therebetween and operative to supply to said recording sheet a negative charge in a pattern which is dependent on a signal derived from signal supplying means as said recording sheet is successively moved with the rotation of said drum. 

1. An electronic printing device comprising a screen of dielectric material impregnated with printing ink; means generating a modulated electron beam signal; means depositing said ink on a recording medium in a pattern representing the strength of said signal by the electrostatic force of attraction between charges of opposite polarity, said depositing means including means supplying a charge of first polarity to said ink in an amount dependent upon the strength of said signal, and means supplying a uniform charge of polarity opposite to that of said first polarity to said recording medium; and means bringing said recording medium and said screen into operative engagement with each other.
 2. An electronic printing device comprising a screen of dielectric material impregnated with printing ink, means for supplying a negative charge of electrons to the ink particles retained within the meshes of said screen in a pattern depending on a signal derived from electron beam generating means thereby negatively charging said ink particles, and transfer printing means bearing a positive charge and operative to cause deposition of said negatively charged ink particles on a recording medium with its positive charge as said recording medium is passed between it and said screen.
 3. An electronic printing device according to claim 2, in which a cathode-ray tube is provided so that the electrical charge in an amount determined by said signal can be transmitted outwardly from said tube through the face plate thereof thereby supplying to said ink particles the negative charge in a pattern which is dependent on the signal.
 4. An electronic printing device comprising a screen of dielectric material impregnated with printing ink; means generating a modulated electron beam signal; means depositing said ink on a recording medium in a pattern representing the strength of said signal by the electrostatic force of attraction between charges of opposite polarity, said depositing means including means supplying a charge of first polarity to said recording medium in an amount dependent upon the strength of said signal and means supplying a uniform charge of a polarity opposite to that of said first polarity to said printing ink; and means bringing said recording medium and said screen into operative engagement with each other.
 5. An electronic printing device according to claim 4, in which a cathode-ray tube is provided so that the electrical charge in an amount determined by said signal can be transmitted outwardly from said tube through the face plate thereof thereby supplying to said recording medium a negative charge in a pattern which is dependent on the signal.
 6. An electronic printing device comprising a screen of dielectric material wound around a drum and impregnated with printing ink, means for supplying a negative charge of electrons to the ink particles retained within the meshes of said screen in a pattern depending on a signal thereby negatively charging said ink particles, and a feed roll bearing a positive charge and operative to feed a recording sheet so that said recording sheet is fed between said roll and said screen.
 7. An electronic printing device comprising a screen of dielectric material wound around a drum and impregnated with printing ink, means for uniformly supplying a positive charge to the ink particles retained within the meshes of said screen, and means disposed opposite to said screen with a recording sheet interposed therebetween and operative to supply to said recording sheet a negative charge in a pattern which is dependent on a signal derived from signal supplying means as said recording sheet is successively moved with the rotation of said drum. 